This invention relates to improvements in pipe gripping tools such as pipe wrenches, pipe vices and chucks.
There have been proposed and practically employed a variety of pipe gripping tools of the above type and in most of these conventional pipe gripping tools, it has been usually practiced that a body is integrally formed at the leading end thereof with a fixed jaw, and a movable jaw is mounted on the body for movement toward and away from the fixed jaw by the operation of an operation member to thereby grip a pipe therebetween and release the pipe therefrom. Thus, the conventional pipe gripping tool has the disadvantage that adjustment of the distance between the gripping faces of the fixed and movable jaws to accommodate pipes having different diameters requires troublesome manual effort. For example such pipe gripping tools are shown in U.S. Pat. No. 2,460,079 and U.S. Pat. No. 1,769,333. Therefore, consideration has been given to forming the body at the leading end thereof with a fixed jaw and having a movable jaw pivoted to the body in opposing relationship to the fixed jaw to grip a pipe therebetween and release the pipe therefrom so as to accomodate pipes having different diameters without any special operation. However, it has been found difficult to design a movable jaw having a bite face which can suitably grip such pipes in cooperation with the opposing bite face on a fixed jaw and thus, such a movable jaw has not yet been practically developed or employed. Therefore, it has been strongly desired to develop a pipe gripping tool which is adapted to suitably grip pipes having different diameters without requiring any special operation.